Based on introduction of genes into cells, it is difficult to control the levels of expressed proteins in each cell. Based on function inhibition represented by siRNA and the antisense method, it is also impossible to repress the function of already-expressed proteins. Especially, when a protein has a long half-life, it is hard to expect its inhibitory effects. Therefore, various attempts have been made to introduce proteins and antibodies into cells.
The known technique for introducing proteins into cells includes methods utilizing cationic liposomes and membrane-permeable peptides. Since the cationic liposome-based delivery performs transfection into cells using charges, it is frequently hard to make preparations because the charge varies from protein to protein, and it is often difficult to perform introduction due to protein charges. The known membrane-permeable peptide-based delivery techniques are those utilizing HIV-derived basic TAT peptides. The reported method of introducing antibodies into cells is a method utilizing a fusion protein consisting of TAT which functions as the membrane-permeable peptide and an antibody-binding region such as Protein A (Patent Document 1). However, the basic membrane-permeable peptide-based introduction of proteins still have problems in scenes wherein intracytoplasmic localization is demanded since basic peptides have nuclear import activity and TAT peptides are known to be transported into the nucleus.
The microinjection-based introduction of proteins and antibodies into cells needs special machinery and tools and also requires extremely complicated operations.
Although, on the basis of inactivated envelope virus delivery for introducing substances into cells, it is known that it is possible to introduce a nucleic acid such as a gene (Patent Document 2) and a protein such as RNase T1 and β-Galactosidase (Non-Patent Documents 1 & 2), it is not said to have enough efficiency to introduce antibodies into cells (Non-Patent Documents 3 & 4).    [Patent Document 1] JP 2005-052083, A    [Patent Document 2] US 2003/0013195 A    [Non-Patent Document 1] European Journal Biochemistry vol. 271, No. 17, 3567-3572, 2004    [Non-Patent Document 2] Neurosci. Lett., 378(1), 18-21, 2005 Apr. 11, 2005    [Non-Patent Document 3] Medical Science Digest vol. 29 (3), 38-41, 2003    [Non-Patent Document 4] Current Gene Therapy, vol. 4, 183-194, 2004